CN111240532A - Silver nanostructure-based optical stack and touch sensor with UV protection - Google Patents

Abstract

Disclosed herein is a touch sensor with a stable and reliable optical stack, comprising a first base transparent conductor having a first substrate and a first plurality of networked silver nanostructures; a cover plate; and a first optically clear adhesive layer, disposed between the cover plate and the first base transparent conductor; wherein the cover plate has a surface for receiving incident light and touch input, and wherein the first optically clear adhesive layer is a UV blocking layer, the first optically transparent adhesive layer and the first plurality of The meshed silver nanostructures are incompatible, and the first optically transparent adhesive layer and the first plurality of meshed silver nanostructures do not come into direct contact with each other. By incorporating one or more UV blocking layers into the touch sensor, yes, touch sensors including silver nanostructure-based optical stacks remain stable against prolonged exposure to light.

Description

Silver nanostructure-based optical stack and touch sensor with UV protection

This application is a divisional application for an invention patent application with an application date of September 25, 2014, an application number of 201480065181.4, and an invention title of "Silver Nanostructure-Based Optical Laminate and Touch Sensor with UV Protection".

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to US Provisional Patent Application No. 61/883,863, filed September 27, 2013, and US Patent Application No. 14/460,999, filed August 15, 2014, which are hereby incorporated by reference in their entirety. refer to.

technical field

The present disclosure is directed to fabricating stable and reliable optical stacks comprising at least one silver nanostructured transparent conductive film.

Background technique

Transparent conductors refer to thin conductive films coated on high transmittance surfaces or substrates. Transparent conductors can be fabricated with surface conductivity while maintaining appropriate optical transparency. Such surface-conductive transparent conductors are widely used as transparent electrodes in flat-panel liquid crystal displays, touch panels, electroluminescent devices, and thin-film photovoltaic cells; as antistatic layers; and as electromagnetic wave shielding layers.

Currently, vacuum deposited metal oxides, such as indium tin oxide (ITO), are the industry standard materials used to provide optical transparency and conductivity to dielectric surfaces such as glass and polymer films. However, metal oxide films are fragile and easily damaged when subjected to bending or other physical stress. They also require high deposition temperatures and/or high annealing temperatures to achieve high levels of conductivity. For certain substrates that tend to absorb moisture, such as plastic and organic substrates (eg, polycarbonate), it is difficult to fully adhere metal oxide films to such substrates. Therefore, the application of metal oxide films to flexible substrates is greatly limited. Additionally, vacuum deposition is an expensive process and requires specialized equipment. In addition, the process of vacuum deposition is not helpful in forming patterns and circuits. This often results in the need for expensive patterning processes, such as photolithography.

In recent years, there has been a trend to replace the current industry standard transparent conductive ITO films in flat panel displays with composite materials consisting of metallic nanostructures (eg silver nanowires) embedded in insulating matrices. Typically, a transparent conductive film is formed by first coating an ink composition comprising silver nanowires and a binder on a substrate. The glue provides an insulating matrix. The resulting transparent conductive film has a sheet resistance comparable to or better than that of the ITO film.

Nanostructure-based coating techniques are particularly suitable for printed electronic devices. Through solution-based structures, printed electronics enables the fabrication of robust electronic devices on large-area flexible substrates or rigid substrates (glass). See US Pat. No. 8,049,333 in the name of Kyberios Technologies, Inc., which is hereby incorporated by reference in its entirety. Solution-based methods for forming nanostructure-based thin films are also compatible with existing coating and lamination techniques. Thus, additional films of overcoats, primers, and adhesive layers can be integrated into a high-throughput process for forming optical stacks that include nanostructure-based transparent conductors.

Although generally considered a precious metal, silver may be susceptible to corrosion under certain circumstances. One result of silver corrosion is a localized or uniform loss of electrical conductivity, which manifests as a drift in sheet resistance of the transparent conductive film, resulting in unreliable performance. Accordingly, there remains a need in the art to provide reliable and stable optical stacks comprising nanostructure-based transparent conductors.

SUMMARY OF THE INVENTION

Disclosed herein are optical stacks comprising silver nanostructure-based optical stacks that are stabilized against prolonged exposure to light by the addition of one or more UV blocking layers.

One embodiment provides a touch sensor comprising: a first base transparent conductor having a first substrate and a first plurality of networked silver nanostructures;

OCA layer,

a second base transparent conductor having a second substrate and a second plurality of networked silver nanostructures; and

the third substrate,

wherein the third substrate has a surface that receives incident light and touch input, the second base transparent conductor is closer to the incident light than the first base transparent conductor, and

wherein at least one of the second substrate, the third substrate or the OCA layer is a UV blocking layer.

A further embodiment provides a touch screen comprising:

a first base transparent conductor having a first substrate and a first plurality of networked silver nanostructures formed on the first substrate;

OCA layer, and

a second base transparent conductor having a second substrate and a continuous conductive film formed on the second substrate;

wherein the second substrate has a surface that receives incident light and touch input, the second base transparent conductor is closer to the incident light than the first base transparent conductor, and

wherein at least one of the second substrate or the OCA layer is a UV blocking layer.

Yet another embodiment provides an optical stack comprising: a base transparent conductor having a substrate and a plurality of networked silver nanostructures; and

UV blocking layer.

Yet a further embodiment provides an optical stack comprising: a base transparent conductor having a first substrate and a plurality of networked silver nanostructures; and

a second substrate covering the base transparent conductor,

wherein the second substrate is coated with a UV blocking coating.

Description of drawings

In the drawings, like reference numerals identify similar elements or acts. The dimensions and relative positions of elements in the figures are not necessarily drawn to scale. For example, the shapes and angles of various elements are not necessarily drawn to scale, and some elements may be arbitrarily enlarged and positioned to improve drawing legibility. Furthermore, the specific shapes of elements as drawn are not intended to convey information regarding the actual shape of a particular element, but are merely selected for ease of identification.

Figure 1 shows an optical stack comprising a base transparent conductor of silver nanostructures.

Figures 2A and 2B schematically illustrate the "edge destruction" mode of nanostructure corrosion.

3-5 illustrate optical stacks incorporating UV blocking layers according to various embodiments of the present disclosure.

Figure 6 shows that "edge damage" is effectively eliminated by adding a UV blocking layer.

7-8 illustrate a touch sensor with a GFF configuration.

9-10 illustrate a touch sensor with an inverted GFF configuration.

11-13 illustrate additionally configured touch sensors according to various embodiments.

Figures 14A and 14B illustrate an example of adding a UV blocking layer to an optical stack.

FIG. 14C shows the light transmittance of the glass compared to the glass laminated with the UV blocking film.

Figure 14D shows the time evolution of the sheet resistance of two optical stacks (1000 and 1060) exposed to light.

Figure 15 shows a comparison of the change in sheet resistance under high intensity light for an optical stack with and without a UV blocking film.

Figure 16 shows a comparison of the change in sheet resistance under low intensity light for an optical stack with and without a UV blocking film.

Figure 17A shows the light irradiance spectrum under certain lighting conditions.

Figure 17B shows the change in sheet resistance of an optical stack without a UV blocking film under certain lighting conditions.

Figures 18A, 18B and 18C show examples of multilayer optical stacks incorporating UV blocking layers and their respective sheet resistances when exposed to light.

Detailed ways

Transparent conductive films are important components in flat panel display devices such as touch screens or liquid crystal displays (LCDs). The reliability of these devices is determined in part by the stability of the transparent conductive films, which will be exposed to light and heat under normal operating conditions of these devices. As will be discussed in more detail below, it has been found that prolonged exposure to light can lead to corrosion of the silver nanostructures, resulting in a localized or uniform increase in the sheet resistance of the transparent conductor. Accordingly, disclosed herein is an optical stack comprising a transparent conductor or film based on silver nanostructures that is stable against prolonged exposure to heat and light, as well as methods for making such an optical stack .

As used herein, an "optical stack" refers to a multilayer structure or panel that is typically placed in the optical path of an electronic device (eg, a touch sensor or a flat panel display). The optical stack includes at least one layer of a metal nanostructure based transparent conductive film (or transparent conductor). Other layers of the optical stack may include, for example, substrates, cover coats, primer coats, adhesive layers, protective layers (eg, cover glass), or other performance enhancing layers, such as antireflective or antiglare films. Preferably, the optical stack includes at least one layer of optically clear adhesive (OCA).

The optical stack can take many configurations. Figure 1 shows one of the simplest constructions. As shown, from bottom to top, the optical stack 10 includes a first substrate 12 , a plurality of networked silver nanostructures 14 , an OCA layer 16 and a second substrate 18 . The optical stack 10 may be formed by first forming the base transparent conductor 20 by depositing a coating solution consisting of silver nanostructures, a binder, and a volatile solvent on the first substrate 12 . After drying and/or curing, the silver nanostructures are immobilized on the first substrate 12 . The first substrate may be a flexible substrate such as a polyethylene terephthalate (PET) film.

第一基板12也可以是刚性材料，比如玻璃。基础透明导体20可以以中间OCA层16介于中间的方式层叠到第二基板18上。第二基板18可以是刚性的(例如玻璃)或者柔性的(例如防护膜)。这种面板例如能够用作电容型触摸面板。The base transparent conductor can be added to various locations within the optical stack. An example of a base transparent conductor 20 is commercially available under the trade name Keborios Technologies, Inc., the patent assignee of the present application

The first substrate 12 may also be a rigid material, such as glass. The base transparent conductor 20 may be laminated to the second substrate 18 with the intermediate OCA layer 16 interposed therebetween. The second substrate 18 may be rigid (eg glass) or flexible (eg pellicle). Such a panel can be used, for example, as a capacitive touch panel.

photooxidation

The silver nanostructures in optical stacks are susceptible to corrosion when exposed to light, which can be attributed to multiple factors acting in complex ways. It has been found that certain corrosion induced by light may be particularly pronounced at the interface of dark and light regions exposed to ambient or simulated light. Figure 2A schematically illustrates this so-called "edge breakage" in an optical stack 30, which can be viewed as a simplified model for a touch sensor. More specifically, the optical stack 30 includes a first substrate 32 for providing a base transparent conductor 40 and a plurality of networked silver nanostructures 34 formed on the first substrate 32, and an OCA layer 36 that provides the base transparent conductor 40. The conductors 40 are bonded to the second substrate 38 . A light-shielding mask 42 is placed along the periphery of the optical stack 30 to mimic the light/dark interface. In a real device, the light/dark interface is created by a "deco frame" or bezel, which is used to hide the signal path traces. The full spectrum light 44 , which is sunlight or light from a sunlight simulator, is directed onto the upper surface 50 of the optical stack 30 . Surprisingly, it can be seen that nanostructures in the illuminated region 56 closest to the interface between the shade and tanning or edge 54 are more likely to occur than nanostructures at the illuminated region 58 farther from the edge 54. faster aging. This aging is manifested by a sudden increase in sheet resistance near edge 54 .

FIG. 2B shows a top view of the optical stack 30 . The light blocking mask 42 blocks light from reaching the underlying local nanostructures. Illuminated regions 56 near mask 42 may experience more and faster nanostructure erosion than regions 58 further away from mask 42 (eg, the center of the touch sensor). Regardless of the destruction mechanism, certain photochemically active reactions were found to lead to corrosion of silver nanostructures through oxidation reactions:

Ag ⁰ →Ag ⁺ +e ^- .

It has been found that two factors promote the oxidation of silver nanowires: ultraviolet (UV) light, and the presence of oxygen in the optical stack. Additionally, polymer-based substrates such as PET may also undergo photo-oxidation when exposed to UV light, which consumes oxygen in the process. The photooxidation rate can also be strongly influenced by the chemicals in other layers in the stack, especially OCA.

Edge localized damage is believed to result from higher local levels of both oxygen and light in regions 56 near the light/dark interface 54 than in regions 58 further away. More specifically, in the illuminated region, silver nanowires are deprived of oxygen due to the competing oxygen consumption of the PET substrate because the PET film substrate is also subjected to photo-oxidation. However, oxygen may diffuse through the PET in the dark area (under the mask), then diffuse laterally through the OCA and into the illuminated area where it is consumed by photo-oxidation reactions. Therefore, the light/dark interface is the only part of the optical stack that is exposed to high levels of oxygen and light.

It has also been found that, in some cases, very close proximity to the OCA appears to cause and exacerbate corrosion of the silver nanostructures. Optically Clear Adhesives (OCA) are thin adhesive films often used to assemble or join several functional layers (eg, cover glass and transparent conductors) into an optical stack or panel (see Figure 1). OCAs often contain mixtures of alkyl acrylates formed by free radical polymerization. As a result, OCA may contain unreacted initiator or photoinitiator, residual monomers, solvent and free radicals. Some chemical species are photosensitizing and may be detrimental to silver nanostructures very close to the OCA. Chemicals from OCA may also contribute to the photo-oxidation reaction by participating in the downstream stages of the redox reaction of the initial photo-oxidation step. As used herein, OCA can be pre-manufactured (including commercial form) and laminated to a substrate, or applied directly to a substrate in liquid form.

Photosensitive chemical species readily absorb photons and undergo or cause complex photochemically active reactions. A photochemically active reaction involves exciting a compound from a ground state to a higher energy level, an excited state. Excited states are transient and generally decay back to the ground state as heat is released. However, such transient excited states can also lead to complex, cascaded reactions with other chemical species.

Add UV blocking layer

Optical stacks incorporating UV blocking layers can block or attenuate the interaction of UV light with silver nanostructures. The UV blocking layer can be added anywhere in the optical stack as long as it is placed between the light source and the nanostructure.

The UV blocking layer includes one or more UV blocking substances that absorb photons in the UV region (generally defined as light below 390 nm), thereby blocking or significantly attenuating ultraviolet light in incident light that would otherwise be possible Enter the optical stack and age the silver nanostructures. UV blocking substances are generally compounds with unsaturated chemical bonds. Generally speaking, when a UV blocking substance absorbs a photon, an electronic excited state is created. The excited state returns to the ground state by energy transfer or electron transfer, thereby dissipating photon energy.

In certain embodiments, the UV blocking layer can be any of the substrates described herein coated with a thin layer of a UV blocking substance. In other embodiments, the UV blocking layer may incorporate one or more UV blocking substances within the bulk of the layer. In further embodiments, the UV blocking layer may be advantageously used as the OCA layer, especially in configurations where the UV blocking layer is an intermediate layer within the optical stack. In this case, the UV blocking OCA layer serves the dual purpose of blocking UV light and joining the two sub-portions of the optical stack.

Figure 3 shows an optical stack 100 incorporating a UV blocking OCA layer. As shown, the optical stack 100 includes a first substrate 112 for providing a base transparent conductor 120 and a plurality of networked silver nanostructures 114 formed on the first substrate 112, a UV blocking OCA layer 116, and a second substrate 118 . A decorative frame or light-shielding mask 122 may optionally be provided at the periphery of the incident light-transmitting surface 124 . This configuration essentially replaces the OCA layer of the optical stack 30 of FIG. 2 with the UV blocking OCA layer 116 . Because the UV blocking OCA layer contacts the nanostructures 114, it is important that the UV blocking OCA is compatible with the nanostructures and does not become a source of instability.

Figure 4 illustrates another embodiment that can address the potential incompatibility between the UV blocking layer and the silver nanostructures by reversing the orientation of the underlying transparent conductor in the optical stack with respect to the incident light. As shown, from bottom to top, the optical stack 150 includes a first substrate 152, a first OCA layer 154, a base transparent conductor 156 including a second substrate 158 and a plurality of networked silver nanostructures 160, a second OCA layer 166 , and a third substrate 168, wherein the second OCA layer 166 is a UV blocking layer, and the silver nanostructures 160 are not in contact with the second OCA layer. A decorative frame or light shielding tape 172 may optionally be provided at the periphery of the surface 174 through which incident light is transmitted. In this configuration, because the base transparent conductor 156 is inverted compared to the base transparent conductor 120 in FIG. 3, the silver nanostructures are no longer in direct contact with the UV blocking OCA layer 166, thereby avoiding UV blocking species and any potential incompatibilities between silver nanostructures. The first OCA layer 154 does not require a UV blocking layer.

FIG. 5 shows a variant configuration derived from FIG. 4 according to another embodiment of the present disclosure. As shown, from bottom to top, the optical stack 200 includes a base transparent conductor 210 having a first substrate 212 and a plurality of networked silver nanostructures 214 , an OCA layer 216 , a second substrate 218 , and a UV blocking layer 220 . The UV blocking layer may optionally be covered by a decorative frame or light-shielding mask 222 in the periphery of the incident light surface 224 . In Figure 5, the silver nanostructures are not in contact with the UV blocking layer, thereby avoiding any potential incompatibilities.

FIG. 6 shows the effect of UV blocking layers obtained by exposing optical stack 30 and optical stack 200 to simulated light conditions, as described herein and below will correspond to an example of optical stack 30 without a UV blocking layer further detailed in panels 3-4 (A). For more than 100 hours of light exposure, significant "edge damage" was exhibited in the edge region 56, as indicated by the apparent abrupt increase in the sheet resistance of the optical stack (measured by the non-contact eddy current method), while in the edge region 56 In bright regions 58 away from edge 54, the sheet resistance of the optical stack is relatively stable. In contrast, the optical stack to which UV blocking layer 220 was added showed the same stability for all optical stacks over 600 hours of light exposure. As demonstrated, the UV blocking layer is effective in preventing localized photoaging.

Test Light Stability

To test the photostability of the optical stack, the sheet resistance of the optical stack exposed to light was measured as a function of time to detect any drift.

The ambient chamber is used as a test facility to provide simulated light and ambient conditions in which the optical stack operates. Typically, xenon arc lamps (eg Atlas XXL+) can be used as daylight simulators. Xenon arc lamps provide full spectrum light that is well matched to sunlight. The intensity of the light can be adjusted to simulate direct sunlight or indirect diffuse sunlight for different time of day or seasons. In addition, the temperature of the environmental chamber (including room temperature and blackboard temperature), relative humidity, and the like can be adjusted.

touch sensor

The UV protective optical stacks described herein can be further integrated with other functional films to form touch sensors.

Whether the touch sensor is capacitive or resistive, one or two transparent conductive films are used under the touch surface to carry the current. The transparent conductive film is patterned into conductive lines to detect the coordinates of the touch input position. When the touch surface is touched, a small change in voltage at the location of the touch input is detected (in resistive touch sensors).

膜)的出现，GFF(玻璃-膜-膜)和G1F(玻璃-膜)配置都是可行的。其他的配置还包括例如由Shoei Co.有限公司提供的P1F(塑料-膜)和由UniDisplay公司提供的OFS(单薄膜方案)。Touch sensors can be constructed using many configurations. Generally, touch sensors can be categorized by different substrates supporting various functional layers, such as glass-based substrates or film-based substrates. Early touch sensor architectures typically employed a GG configuration, a glass-to-glass structure, with each glass substrate supporting a corresponding transparent conductive film (eg, an ITO layer). With thin film-based transparent conductors such as those offered by Cabrios Technologies

membrane), GFF (glass-membrane-membrane) and G1F (glass-membrane) configurations are both feasible. Other configurations include, for example, P1F (Plastic-Film) offered by Shoei Co. Ltd. and OFS (Single Film Scheme) offered by UniDisplay Corporation.

Regardless of the configuration, at least one layer (eg, substrate, capping layer, or OCA layer) should be a UV blocking layer between the incident light and the silver nanostructures. When two silver nanostructured layers are present, the UV blocking layer should be between the incident light and the silver nanostructured layer closer to the incident light, eg, between the incident light and the second base transparent conductor layer described herein.

Various embodiments relate to touch sensor architectures implemented by adding one or more UV blocking layers that provide photostability and protect silver nanostructures from photoaging. It should be understood that all configurations discussed herein may further include one or more antioxidants and/or one or more oxygen barrier layers as described in co-pending US Patent Application No. 14/181,523, which It is hereby incorporated in its entirety.

膜。第二基础透明导体316进一步以UV阻挡OCA层326介于中间的方式接合至第三基板328。第三基板可以是接收入射光和触摸输入的盖板玻璃。可以在盖板玻璃328的下方加入可选的装饰框330。UV阻挡OCA层326有效地阻挡入射光中的紫外光越过盖板玻璃而进入光学叠层。FIG. 7 shows an exemplary GFF (glass-film-film) configuration according to one embodiment. As shown, from bottom to top, the touch sensor 300 includes a first base transparent conductor 310 having a first substrate 312 and a first plurality of networked silver nanostructures 314 formed on the first substrate 312 . The first base transparent conductor 310 is bonded with the OCA layer 318 interposed to a second base transparent conductor 316 having a second substrate 322 and a second plurality of interconnected silvers formed on the second substrate 322 Nanostructures 324. Each of the first and second base transparent conductors may be

membrane. The second base transparent conductor 316 is further bonded to the third substrate 328 with the UV blocking OCA layer 326 interposed. The third substrate may be a cover glass that receives incident light and touch input. An optional decorative frame 330 may be added below the cover glass 328 . The UV blocking OCA layer 326 effectively blocks ultraviolet light in incident light from passing through the cover glass and into the optical stack.

膜。第二基础透明导体416进一步以OCA层426介于中间的方式接合至第三基板428，第三基板428是UV阻挡盖板镜片(塑料或者镀膜玻璃)。可以在UV阻挡盖板镜片428的下方加入可选的装饰框430。UV阻挡盖板镜片428有效地阻挡入射光中的紫外光进入触摸传感器。Figure 8 shows a GFF/PFF (plastic-film-film) configuration according to another embodiment. As shown, from bottom to top, touch sensor 400 includes a first base transparent conductor 410 having a first substrate 412 and a first plurality of networked silver nanostructures 414 formed on the first substrate 412 . The first base transparent conductor 410 is bonded with the OCA layer 418 interposed to a second base transparent conductor 416 having a second substrate 422 and a second plurality of interconnected silvers formed on the second substrate 422 Nanostructures 424. Each of the first and second base transparent conductors may be

membrane. The second base transparent conductor 416 is further bonded to a third substrate 428, which is a UV blocking cover lens (plastic or coated glass), with the OCA layer 426 in between. An optional decorative frame 430 may be added below the UV blocking cover lens 428 . The UV blocking cover lens 428 effectively blocks ultraviolet light in the incident light from entering the touch sensor.

膜。第二基础透明导体530进一步以UV阻挡OCA层536介于中间的方式接合至第三基板538。第三基板538可以是接收入射光和触摸输入的盖板玻璃。可以在盖板玻璃538的下方加入可选的装饰框540。UV阻挡OCA层536有效地阻挡入射光中的紫外光越过盖板玻璃而进入光学叠层。另外，因为第二基础透明导体被反转以使得第二基板532比第二多个纳米结构534更靠近入射光，所以纳米结构534不直接接触UV阻挡OCA层536。因而，纳米结构和UV阻挡OCA层之间的任何潜在不兼容性不会导致触摸传感器不稳定。FIG. 9 shows a touch sensor in another GFF configuration in which the underlying transparent conductor is reversed compared to that in FIG. 7 . As shown, from bottom to top, the touch sensor 500 includes a cover film/display layer 510 bonded to a first base transparent conductor 520 with a first OCA layer 512 in between, the first base The transparent conductor layer 520 has a first substrate 522 and a first plurality of networked silver nanostructures 524 formed on the first substrate 522 . Compared to the first base transparent conductor 310 of FIG. 7 , the first base transparent conductor 520 is inverted so that the first substrate 522 is closer to the incident light than the nanostructures 524 . The first base transparent conductor 520 is bonded with the OCA layer 526 interposed to a second base transparent conductor 530 having a second substrate 532 and a second plurality of interconnected silvers formed on the second substrate 532 Nanostructures 534. Each of the first and second base transparent conductors may be

membrane. The second base transparent conductor 530 is further bonded to the third substrate 538 with the UV blocking OCA layer 536 interposed. The third substrate 538 may be a cover glass that receives incident light and touch input. An optional trim frame 540 may be added below the cover glass 538 . UV blocking OCA layer 536 effectively blocks ultraviolet light in incident light from passing through the cover glass and into the optical stack. Additionally, because the second base transparent conductor is inverted so that the second substrate 532 is closer to the incident light than the second plurality of nanostructures 534 , the nanostructures 534 do not directly contact the UV blocking OCA layer 536 . Thus, any potential incompatibility between the nanostructures and the UV blocking OCA layer will not lead to instability of the touch sensor.

膜。UV阻挡基板632可以是涂有一种或多种UV阻挡物质的任何基板。第二基础透明导体630进一步以UV阻挡OCA层636介于中间的方式接合至第三基板638。可以在盖板玻璃638的下方加入可选的装饰框640。在这种配置中，第二基础透明导体630的反转结构使得位于入射光和纳米结构634之间的UV阻挡基板632能够阻挡紫外光与纳米结构相互作用。Figure 10 shows a touch sensor in another GFF configuration in which the underlying transparent conductor is inverted. The touch sensor 600 is similar to the touch sensor 500 in FIG. 9 except that the second base transparent conductor 630 has a UV blocking substrate. More specifically, from bottom to top, touch sensor 600 includes cover film/display layer 610 bonded to first base transparent conductor layer 620 with first OCA layer 612 interposed, first The base transparent conductor layer 620 has a first substrate 622 and a first plurality of networked silver nanostructures 624 formed on the first substrate 622 , the first substrate 622 being closer to the incident light than the nanostructures 624 . The first base transparent conductor 620 is bonded to the second base transparent conductor 630 with the OCA layer 626 interposed, and the second base transparent conductor 630 has a second UV blocking substrate 632 and a second base transparent conductor 632 formed on the second UV blocking substrate 632. A plurality of networked silver nanostructures 634. Each of the first and second base transparent conductors may be

membrane. UV blocking substrate 632 may be any substrate coated with one or more UV blocking substances. The second base transparent conductor 630 is further bonded to the third substrate 638 with the UV blocking OCA layer 636 interposed. An optional trim frame 640 may be added below the cover glass 638 . In this configuration, the inverted structure of the second base transparent conductor 630 enables the UV blocking substrate 632 located between the incident light and the nanostructures 634 to block UV light from interacting with the nanostructures.

膜。第一基础透明导体层710以UV阻挡OCA层720介于中间的方式接合至基于玻璃的透明导体730，所述基于玻璃的透明导体730具有玻璃基板732和在玻璃基板732上形成的连续导电膜734，所述连续导电膜734例如是一层ITO膜，所述ITO膜接触UV阻挡OCA层720。可以在盖板玻璃732的下方加入可选的装饰框740。Figure 11 shows a touch sensor with a G1F configuration. From bottom to top, the touch sensor 700 includes a first base transparent conductor layer 710 having a first substrate 712 and a first plurality of networked silver nanostructures 714 formed on the first substrate 712 . The first base transparent conductor layer 710 may be

membrane. The first base transparent conductor layer 710 is bonded with the UV blocking OCA layer 720 interposed to the glass-based transparent conductor 730 having a glass substrate 732 and a continuous conductive film formed on the glass substrate 732 734 , the continuous conductive film 734 is, for example, an ITO film, and the ITO film contacts the UV blocking OCA layer 720 . An optional decorative frame 740 may be added below the cover glass 732 .

膜。所述第一基础透明导体层810以OCA层820介于中间的方式接合至第二基础透明导体830，第二基础透明导体830具有第二UV阻挡基板832和在第二UV阻挡基板832上形成的第二多个联网银纳米结构834。第二多个联网银纳米结构834接触OCA层820。第二UV阻挡基板832可以是接收入射光和触摸输入的塑料盖板镜片。可以在盖板镜片832的下方加入可选的装饰框840。Figure 12 shows a touch sensor with a P1F configuration employing a UV blocking plastic cover lens. More specifically, from bottom to top, the touch sensor 800 includes a first base transparent conductor layer 810 having a first substrate 812 and a first plurality of networked silver nanometers formed on the first substrate 812 Structure 814. The first base transparent conductor layer 810 may be

membrane. The first base transparent conductor layer 810 is bonded to the second base transparent conductor 830 with the OCA layer 820 interposed therebetween, and the second base transparent conductor 830 has a second UV blocking substrate 832 and is formed on the second UV blocking substrate 832 834 of the second plurality of networked silver nanostructures. The second plurality of networked silver nanostructures 834 contacts the OCA layer 820 . The second UV blocking substrate 832 may be a plastic cover lens that receives incident light and touch input. An optional decorative frame 840 may be added below the cover lens 832.

膜。第一基础透明导体层910直接接合至第二基础透明导体920，第二基础透明导体920具有第二基板922和在第二基板922上形成的第二多个纳米结构924。第二基板922用作直接接合至第一多个纳米结构914的OCA层。适当的材料包括由日立公司提供的TCTF(可转印透明导电膜)，其中第二基板由透明的可光致固化的转印膜构成，这种转印膜可通过层叠工艺应用至第一基础透明导体。第二基础透明导体920进一步以UV阻挡OCA层930介于中间的方式接合至第三基板932，例如盖板玻璃。可以在盖板镜片932的下方加入可选的装饰框940。Figure 13 shows a touch sensor with an OFS configuration employing a single film solution to fabricate two base transparent conductors directly bonded to each other without an intervening OCA layer. From bottom to top, the touch sensor 900 includes a first base transparent conductor layer 910 having a first substrate 912 and a first plurality of networked silver nanostructures 914 formed on the first substrate 912 . The first base transparent conductor layer 910 may be

membrane. The first base transparent conductor layer 910 is directly bonded to a second base transparent conductor 920 having a second substrate 922 and a second plurality of nanostructures 924 formed on the second substrate 922 . The second substrate 922 serves as the OCA layer directly bonded to the first plurality of nanostructures 914 . Suitable materials include TCTF (Transparent Conductive Transfer Film) supplied by Hitachi, where the second substrate consists of a transparent photocurable transfer film that can be applied to the first base by a lamination process transparent conductor. The second base transparent conductor 920 is further bonded to a third substrate 932, such as a cover glass, with the UV blocking OCA layer 930 interposed. An optional decorative frame 940 may be added below the cover lens 932.

Certain other features of the present disclosure are discussed in greater detail further below.

silver nanostructures

As used herein, "silver nanostructures" generally refer to electrically conductive nanoscale structures, wherein at least one dimension (ie, width or diameter) is less than 500 nm; more typically, less than 100 nm or 50 nm. In various embodiments, the nanostructures have widths or diameters in the range of 10 to 40 nm, 20 to 40 nm, 5 to 20 nm, 10 to 30 nm, 40 to 60 nm, or 50 to 70 nm.

Nanostructures can have any shape or geometry. One way to define the geometry of a given nanostructure is by its "aspect ratio," which refers to the ratio of the nanostructure's length and width (or diameter). In certain embodiments, the nanostructures are isotropically shaped (ie, aspect ratio=1). Typical isotropic or substantially isotropic nanostructures include nanoparticles. In a preferred embodiment, the nanostructures are anisotropically shaped (ie, aspect ratio ≠ 1). Anisotropic nanostructures typically have a longitudinal axis along their length. Exemplary anisotropic nanostructures include nanowires (solid nanostructures with an aspect ratio of at least 10, more typically, an aspect ratio of at least 50), nanorods (solid nanostructures with an aspect ratio of less than 10), and nanotubes (hollow nanostructures).

The lengths of longitudinally anisotropic nanostructures (eg nanowires) are greater than 500 nm, or greater than 1 μm, or greater than 10 μm. In various embodiments, the nanostructures have lengths in the range of 5 to 30 μm, alternatively in the range of 15 to 50 μm, 25 to 75 μm, 30 to 60 μm, 40 to 80 μm, or 50 to 100 μm.

Typically, silver nanostructures have an aspect ratio in the range of 10 to 100,000. Larger aspect ratios are advantageous for obtaining transparent conductor layers because they enable lower overall wire density for high transparency while enabling the formation of more efficient conductive networks. In other words, when conductive nanowires with high aspect ratios are used, the density of nanowires implementing the conductive network can be low enough to make the conductive network substantially transparent.

Silver nanowires can be prepared by methods known in the art. In particular, silver nanowires can be synthesized by liquid phase reduction of silver salts such as silver nitrate in the presence of polyols such as ethylene glycol and polyvinylpyrrolidone. Large-scale production of silver nanowires of uniform size can be accomplished according to U.S. Published Application Nos. 2008/0210052, 2011/0024159, 2011/0045272, and 2011, all in the name of Kyberios Technologies, Inc., the assignee of the present disclosure /0048170 to prepare and refine.

nanostructured layer

The nanostructure layer is a conductive network of networked metal nanostructures (eg, silver nanowires) that provide an electrically conductive medium for transparent conductors. Since conductivity is achieved by charge percolating from one metal nanostructure to another, enough metal nanowires must be present in the conducting network to reach the electropercolation threshold and become conductive. The surface conductivity of a conductive network is inversely proportional to its surface resistivity, sometimes referred to as sheet resistance, and can be measured by methods known in the art. As used herein, "electrically conductive" or simply "conductive" corresponds to a surface resistivity of no greater than 10 ⁴ Ω/D, or more typically no greater than 1,000 Ω/D, or more typically no greater than 500 Ω/D □, or more typically no more than 200Ω/□. Surface resistivity depends on factors such as the aspect ratio, degree of alignment, degree of agglomeration, and resistivity of the networked metal nanostructures.

之类的具有高芳香度的聚合物，聚苯乙烯，聚甲基苯乙烯(polyvinyltoluene)，聚乙二烯(polyvinylxylene)，聚酰亚胺，聚酰胺，聚酰胺亚胺，聚醚酰亚胺，聚硫化物，聚砜，聚苯，以及聚苯醚，聚氨基甲酸酯(PU)，环氧，聚烯烃(例如，聚丙烯，聚甲基戊烯，和环烯烃(cyclic olefins))，丙烯腈-丁二烯-苯乙烯共聚物(ABS)，纤维素，硅酮及其他含硅聚合物(例如，聚倍半硅氧烷和聚硅烷)，聚氯乙烯(PVC)，多醋酸盐(polyacetates)，聚降冰片烯(polynorbornenes)，合成橡胶(例如，EPR，SBR，EPDM)，和含氟聚合物(例如，聚偏二氟乙烯，聚四氟乙烯(TFE)或者聚六氟丙烯)，荧光烯烃和烃烯烃的共聚物(例如，

)，非晶氟碳聚合物或者共聚物(例如由Asahi Glass公司提供的

或者由杜邦公司提供的

AF)。In certain embodiments, metal nanostructures can form conductive networks on substrates without the use of adhesives. In other embodiments, a glue may be provided to facilitate adhesion of the nanostructures to the substrate. Suitable adhesives include optically clear polymers including, but not limited to, polyacrylates such as polymethacrylates (eg, poly(methyl methacrylate)), polyacrylates and Polyacrylonitrile, polyvinyl alcohol, polyesters (eg, polyethylene terephthalate (PET), polyethylene naphthalate, and polycarbonate), such as phenolic resins or cresol formaldehyde resin

Highly aromatic polymers such as polystyrene, polyvinyltoluene, polyvinylxylene, polyimide, polyamide, polyamidoimide, polyetherimide , polysulfides, polysulfones, polyphenylenes, and polyphenylene oxides, polyurethanes (PU), epoxies, polyolefins (eg, polypropylene, polymethylpentene, and cyclic olefins) , acrylonitrile-butadiene-styrene copolymer (ABS), cellulose, silicone and other silicon-containing polymers (eg, polysilsesquioxane and polysilane), polyvinyl chloride (PVC), polyester Polyacetates, polynorbornenes, synthetic rubbers (eg, EPR, SBR, EPDM), and fluoropolymers (eg, polyvinylidene fluoride, polytetrafluoroethylene (TFE), or polyhexanol) fluoropropylene), copolymers of fluorescent olefins and hydrocarbon olefins (e.g.,

), amorphous fluorocarbon polymers or copolymers (such as those available from Asahi Glass

or provided by DuPont

AF).

"Substrate" refers to a non-conductive material on which metal nanostructures are coated or laminated. The substrate can be rigid or flexible. The substrate may be transparent or opaque. Suitable rigid substrates include, for example, glass, polycarbonate, acrylic, and the like. Suitable flexible substrates include, but are not limited to, polyesters (eg, polyethylene terephthalate (PET), polyethylene naphthalate, and polycarbonate), polyolefins (eg, linear, branched, and cyclic polyolefins), polyethylene (eg, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetal, polystyrene, polyacrylates, etc.), cellulose ester bases (eg, cellulose triacetate, cellulose acetate), polysulfones such as polyethersulfone, polyimide, silicone, and other conventional polymer membranes. Additional examples of suitable substrates can be found, for example, in US Pat. No. 6,975,067.

Once the nanostructured layer is formed on the substrate, a base transparent conductor is created. The base transparent conductor can be further integrated with other functional layers/films to form an optical stack.

Typically, the optical transparency or transparency of a transparent conductor (ie, a conductive network on a non-conductive substrate) can be quantitatively defined by parameters including light transmission and haze. "Light transmittance" (or "light transmittance") refers to the percentage of incident light that is transmitted through a medium. In various embodiments, the light transmittance of the conductive layer is at least 80%, and can be as high as 98%. Performance enhancing layers such as adhesive layers, anti-reflection layers or anti-glare layers may result in a further reduction in the overall light transmission of the transparent conductor. In various embodiments, the light transmission (T%) of the transparent conductor can be at least 50%, at least 60%, at least 70%, or at least 80%, and can be as high as at least 91 to 92%, Or at least 95%.

Haze (H%) is a measure of light scattering. Haze refers to the amount of light that is separated from incident light and scattered during transmission. Unlike light transmission, which is essentially a property of the medium, haze is a constant manufacturing concern and is often caused by surface roughness as well as embedded particles or compositional inhomogeneities in the medium. Typically, the haze of a conductive film can be significantly affected by the diameter of the nanostructures. Larger diameter nanostructures (eg, thicker nanowires) are generally associated with higher haze. In various embodiments, the haze of the transparent conductor is no more than 10%, no more than 8%, or no more than 5%, and may be as low as no more than 2%, no more than 1%, or no more than 0.5%, or no more than more than 0.25%.

coating composition

Patterned transparent conductors according to the present disclosure are prepared by coating a nanostructure-containing coating composition on a non-conductive substrate. To form coating compositions, metal nanowires are typically dispersed in a volatile liquid to facilitate the coating process. It should be understood that, as used herein, any non-corrosive volatile liquid in which the metal nanowires can form stable dispersions can be used. Preferably, the metal nanowires are dispersed in water, alcohols, ketones, ethers, hydrocarbons or aromatic solvents (benzene, toluene, xylene, etc.). More preferably, the liquid is volatile and has a boiling point of no more than 200°C, no more than 150°C, or no more than 100°C.

)。In addition, the metal nanowire dispersions may contain additives and binders to control viscosity, corrosion, adhesion, and nanowire dispersibility. Examples of suitable additives and binders include, but are not limited to: carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), methyl cellulose (MC) , polyvinyl alcohol (PVA), tripropylene glycol (TPG) and xanthan gum (XG), and surfactants such as ethoxylates, alkoxylates, ethylene oxide ) and propylene oxide and their copolymers, sulfonates, sulfates, disulfonates, sulfosuccinates, phosphate esters and fluorosurfactants (eg, by Provided by DuPont

).

FSO-100来说是从0.0025％至0.05％)，从0.02％至4％的粘度调节剂(例如，优选范围对于HPMC来说是0.02％至0.5％)，从94.5％至99.0％的溶剂，以及从0.05％至1.4％的金属纳米线。适当的表面活性剂的代表性实例包括

FSN，

FSO，

FSH，Triton(x100，x114，x45)，Dynol(604，607)，n-Dodecyl b-D-maltoside和Novek。适当的粘度调节剂的实例包括羟丙基甲基纤维素(HPMC)、甲基纤维素、黄原胶、聚乙烯醇、羧甲基纤维素和羟乙基纤维素。适当的溶剂的实例包括水和异丙醇。In one example, the nanowire dispersion or "ink" includes from 0.0025% to 0.1% by weight of surfactant (eg, the preferred range for

From 0.0025% to 0.05% for FSO-100), from 0.02% to 4% viscosity modifier (eg, the preferred range is 0.02% to 0.5% for HPMC), from 94.5% to 99.0% solvent, and metal nanowires from 0.05% to 1.4%. Representative examples of suitable surfactants include

FSN,

FSO,

FSH, Triton (x100, x114, x45), Dynol (604, 607), n-Dodecyl bD-maltoside and Novek. Examples of suitable viscosity modifiers include hydroxypropyl methylcellulose (HPMC), methylcellulose, xanthan gum, polyvinyl alcohol, carboxymethylcellulose, and hydroxyethylcellulose. Examples of suitable solvents include water and isopropanol.

The nanowire concentration in the dispersion can affect or determine parameters such as thickness, conductivity (including surface conductivity), optical transparency, and mechanical properties of the nanowire network layer. The percentage of solvent can be adjusted to provide the desired concentration of nanowires in the dispersion. However, in preferred embodiments, the relative ratios of the other ingredients may remain the same. In particular, the ratio of the surfactant to the viscosity modifier is preferably in the range of about 80 to about 0.01; the ratio of the viscosity modifier to the metal nanowire is preferably in the range of about 5 to about 0.000625; the metal The ratio of nanowires to surfactant is preferably in the range of about 560 to about 5. The ratios of the components of the dispersion can be modified depending on the substrate used and the coating method. The preferred viscosity range for nanowire dispersions is between about 1 and 100 cP.

After coating, the volatile liquid is removed by evaporation. Evaporation can be accelerated by heating (eg, baking). The resulting nanowire network layer may require subsequent processing to make it electrically conductive. This subsequent treatment may be a treatment step comprising exposure to heat, plasma, corona discharge, UV-ozone or pressure as described below.

Examples of suitable coating compositions are described in U.S. Published Application Nos. 2007/0074316, 2009/0283304, 2009/0223703, and 2012/0104374, all in the name of Kyberios Technologies, Inc., the assignee of the present disclosure .

The coating composition is applied to the substrate by, for example, sheet coating, web coating, printing and lamination to provide transparent conductors. Additional information for making transparent conductors from conductive nanostructures is disclosed, for example, in US Published Patent Application Nos. 2008/0143906 and 2007/0074316 in the name of Kyberios Technologies, Inc.

The transparent conductor structures, their electrical and optical properties, and patterning methods will be illustrated in more detail by the following non-limiting examples.

Example

Example 1

Synthesis of Silver Nanowires

Silver nanowires were synthesized by reduction of silver nitrate dissolved in ethylene glycol in the presence of polyvinylpyrrolidone (PVP), following for example Y. Sun, B. Gates, B. Mayers and Y. The "polyol" method described by Xia in "Crystalline silver nanowires by soft solution processing" published by Nanoletters (2002), 2(2) 165-168. The improved polyol process described in U.S. Published Application Nos. 2008/0210052 and 2011/0174190 in the name of Cabrios Technologies, Inc. produces more uniform silver nanoparticles at higher yields than conventional "polyol" processes Wire. All of these applications are hereby incorporated by reference in their entirety.

Example 2

Standard Membrane Manufacturing Process

FSA之类的氟表面活性剂)。所述墨水以狭缝模具(slot-die)、卷装进出(roll-to-roll)的方式涂布在PET膜(例如，MELINEX-454或者TORAY U483)上，并且使所述墨水干燥以形成纳米线层。对于某些实施例，随后在所述纳米线层上涂敷聚合物覆盖涂层。An ink composition is prepared that includes silver nanowires, a cellulose-based binder, and a surfactant (eg, such as

Fluorosurfactants such as FSA). The ink is applied on a PET film (eg, MELINEX-454 or TORAY U483) in a slot-die, roll-to-roll manner, and the ink is allowed to dry to A nanowire layer is formed. For certain embodiments, a polymer capcoat is subsequently applied over the nanowire layer.

The roll-to-roll process can accommodate a wide variety of substrate and film sizes. Suitable in-roll deposition processes may include, but are not limited to, slot die, gravure, reverse gravure, microgravure, reverse roll, and Mayerbar. A more detailed description of the in-and-out process can be found in US Patent No. 8,049,333 and US Published Patent Application No. 2013/0040106 in the name of the assignee of the present application, Kyberios Technologies, Inc. Both of these patent documents are hereby incorporated by reference in their entirety.

Example 3

Light stability of films with and without UV blocking layer

A sample optical stack 1000 without the UV blocking layer is shown in Figure 14A. First, a base transparent conductive film 1010 having a PET substrate 1020 and a networked silver nanowire layer 1030 was fabricated according to Example 2. Subsequently, the base transparent conductive film was mounted on a piece of Eagle XG glass 1040 and secured with tape 1050 around the edges. The nanowires 1030 face the glass 1040 and are in loose contact with the glass 1040, but are bonded to the glass 1040 without any adhesive. To illustrate this configuration, the air gap 1044 is shown schematically.

Another sample optical stack 1060 with a UV blocking layer is shown in FIG. 14B, which may be based on the optical stack 1000 of FIG. 14A by laminating on the surface of the glass opposite the nanowires UV blocking film 1070 is produced.

Figure 14C shows the transmission spectrum of bare Eagle XG glass, compared to the transmission spectrum of glass laminated with a UV blocking film. As shown, while the glass allows transmission of up to 90% of UV light (below 370 nm), glass with a UV blocking layer blocks nearly all light below 370 nm (near zero transmission).

The sheet resistance of each film was measured using a Delcom 717 non-contact resistance meter. The average sheet resistance is approximately 130 ohms/square.

The samples were placed in an Atlas XXL+ Xenon Lamp Weathering Machine with an Atlas "Daylight" filter. The sample is oriented so that the glass is between the film and the light source. The light intensity was set to 0.8W/m2*nm at 420nm, and the spectrum and intensity closely matched direct sunlight. The environmental conditions are set to:

38℃ room temperature

60°C blackboard temperature, and

50% relative humidity.

Periodically samples are removed and electrical measurements are taken.

Figure 14D shows the time evolution of sheet resistance for the two samples (optical stacks 1000 and 1060). It can be seen that the increase in sheet resistance is much slower when the UV portion of the incident light is blocked.

Example 4

Light Stability of Laminated Films with UV Blocking Layers

A base transparent conductive film was prepared according to Example 2. The average sheet resistance of the film was 130 ohms/sq. Each film was laminated to each Eagle XG glass with an OCA layer (3M 8146-2) with the nanowire layer in contact with the OCA layer and facing the glass. For some samples, UV blocking films were applied to opposite surfaces of the glass. For all samples, black electrical tape was applied to the surface of the glass opposite the nanowire layer so that half of the sample was covered with black tape. The sample configuration is the same as the embodiment shown in FIG. 3 .

Sample size is 2" x 3". Sheet resistance was measured using a Delcom 717 non-contact sheet resistance meter at three locations: the center of the dark area, the center of the light area, and at the light/dark interface (the "edge", although this is not the physical edge of the sample) . Delcom uses eddy current to measure sheet resistance, and the sensing radius is about 1 cm.

The samples were placed in the xenon arc chamber described in Example 3 with the glass side up under the same test conditions. The samples were removed at various times and the electrical measurements were repeated. The data is shown in Figure 15. For the samples without the UV blocking layer, at some time between 75 and 150 hours, the sheet resistance signal increased sharply at the edge locations, while the sheet resistance did not increase in the dark and light regions.

For the samples with the UV blocking film, no appreciable change in sheet resistance was observed until approximately 300 hours of light exposure. After more than 300 hours, the sheet resistance increased uniformly in the illuminated region, rather than specifically at the light-dark interface. Thus, blocking the UV portion of the spectrum can increase sample lifetime and allow for a change in damage mode.

Thus, the net effect of blocking the UV portion of the light appears to be improved durability to light exposure before an appreciable increase in resistance occurs in any portion of the sample.

Example 5

Photostability of Films with UV Blocking Layers under Reduced Intensity Simulated Sunlight

A sample of the base transparent conductive film was prepared essentially the same as the sample described in Example 2. The samples were placed in a metal baking pan with a folded edge with the glass side up. The pan was then covered with three layers of wire mesh screens having mesh counts of 60, 100 and 325 wires per inch. The combined transmittance of the triple mesh screen was approximately 5% when measured with a spectrophotometer and was substantially independent of wavelengths above 300 nm. The mesh screen is clamped to the edge of the pan to prevent stray light from entering.

Under the same conditions as in Examples 3 and 4, the baking pan was placed into a xenon arc chamber, and the samples were periodically removed to obtain electrical properties. Although the light source in the xenon arc chamber was the same as in Examples 3 and 4, the wire mesh reduced the intensity of light incident on the sample.

The results are shown in FIG. 16 . The sheet resistance of the control sample (without the UV blocking layer) continued to increase and was a 100% increase in about 200 hours. Contrary to the results of Example 2, which showed "edge destruction", the increase in resistance at the edge lagged behind the stronger increase in the illuminated area. Surprisingly, even though the light intensity has been reduced by a factor of 20, the timing of the destruction is not slightly different. This is believed to be a result of the photo-oxidation reaction under full-intensity xenon light being mainly limited by oxygen diffusion (rather than light intensity).

In contrast, the samples with the UV blocking layer were stable for at least 1300 hours.

Example 6

Photostability of films exposed to indirect light through windows

A sample with a similar structure to the previous example was prepared and placed next to two different north facing windows in an office building. The windows were dyed to a similar shade of grey, but their UV transmission differed. Irradiance spectra for two windows over a few minutes were acquired at 11 am using an Atlas LS200 calibrated spectrometer and are shown in Figure 17A. Spectra obtained by placing the spectrometer under a blue sky (no direct sunlight, only diffuse sunlight) and directly under the sun are also shown for reference. Both were obtained outdoors on a sunny day at the same time. It can be seen that window #2 transmits about ten times less UV light than window #1.

The resistance data for the sample next to the two windows (without the inner UV blocking layer) is shown in Figure 17B. The samples behind the window with lower UV transmission were more stable, again demonstrating the benefit of UV blocking.

Example 7

Adding UV blocking layers to optical stacks

The UV blocking layer can be added directly to the optical film stack of the touch sensor structure without the need to apply a UV blocking coating or film to the cover glass lens. Samples were prepared using the structures shown in Figures 18A and 18B.

FIG. 18A shows the configuration of the optical stack 1100 . More specifically, the base transparent conductive film 1110 is shown bonded to the glass cover plate 1130 with the UV blocking OCA layer 1120 interposed. The base transparent conductive film 1110 includes a substrate 1112 and a plurality of networked silver nanowires 1114 . The substrate 1112 may be a PET film. The UV blocking OCA layer is 3M 8172PCL and is in direct contact with the silver nanowires 1114. In Figure 18A, a light-shielding mask 1140 is shown on the periphery of the optical stack 1100 to mimic the dark/light interface.

膜)的基板。While some of the chemistries in the UV blocking OCA layer interact with, or are incompatible with, the silver nanowires, it is preferred that the UV blocking OCA layer and the silver nanowires do not come into direct contact with each other. Therefore, in an alternative configuration, an interference layer is added between the UV blocking layer and the silver nanowires. FIG. 18B shows that the interference layer may be a base transparent conductive film (

film) substrate.

More specifically, in FIG. 18B, the optical stack 1200 is constructed by bonding the first substrate 1210 to the base transparent conductive film 1110 with the first OCA layer 1220 interposed, the base transparent conductive film 1110 including the first OCA layer 1220. Two substrates 1112 and a plurality of interconnected silver nanowires 1114 . The first OCA layer 1220 need not block UV light, but is chosen to be chemically compatible with the silver nanowires 1114 so that direct contact with the silver nanowires does not destabilize them. An example of the first OCA layer is 3M 8146. Alternatively, the first OCA layer may be an optically clear resin (OCR) layer, including any OCR layer known in the art for directly bonding a touch sensor to a display. The first substrate 1210 and the second substrate 1112 may be PET films. In alternative embodiments, the first substrate may also include a display.

Subsequently, the base transparent conductive film 1110 is bonded to the glass cover plate 1130 with the UV blocking OCA layer 1120 interposed therebetween. Unlike FIG. 18A, FIG. 18B shows the base transparent conductive film 1110 contacting the UV blocking OCA layer 1120 through its substrate 1120, thereby avoiding direct contact between the silver nanowires 1114 and the UV blocking OCA layer. An example of a UV blocking layer is 3M 8172PCL. In Figure 18B, a light-shielding mask 1140 is shown on the periphery of the optical stack 1200 to mimic the dark/light interface.

In both configurations, a UV blocking OCA layer 1120 is employed which serves the dual function of bonding and blocking the UV region of the spectrum incident on the optical stack. These configurations eliminate the need to apply a separate UV blocking coating. However, additional UV blocking coatings can also be provided, eg on the glass cover plate.

The light stability of the optical stack was tested in the same manner as in Example 3. In this example, sheet resistance data was collected only at the light exposure location and the light/dark interface location. FIG. 18C shows the variation in sheet resistance of optical stack 1100 and optical stack 1200 . The optical stack 1100 exhibits poor photostability, most likely due to destabilization or aging of the silver nanowires caused by incompatibility between the silver nanowires and the UV blocking OCA layer.

On the other hand, the optical stack 1200 exhibited photostability over a 500 hour light exposure period. This result suggests that the UV-blocking OCA layer is able to stabilize the performance of the optical stack by blocking UV light by avoiding direct contact between the incompatible UV-blocking OCA and the silver nanowires.

All of the above US patents, US patent application publications, US patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and listed in the Application Data Sheet are hereby incorporated in their entirety. for reference.

It will be understood from the foregoing that although specific embodiments of the invention are described herein for illustrative purposes, various modifications may be made without departing from the spirit and scope of the invention.

Claims (10)

1. A touch sensor comprising: a first base transparent conductor having a first substrate and a first plurality of networked silver nanostructures; cover; and a first optically transparent adhesive layer disposed between the cover plate and the first basic transparent conductor; wherein the cover plate has a surface that receives incident light and touch input, and wherein the first optically clear adhesive layer is a UV blocking layer, the first optically clear adhesive layer is incompatible with the first plurality of networked silver nanostructures, the first optically clear adhesive layer and the first plurality of interconnected silver nanostructures are incompatible. The networked silver nanostructures do not come into direct contact with each other. 2. The touch sensor of claim 1, wherein there is an interference layer between the first optically clear adhesive layer and the first plurality of networked silver nanostructures. 3. The touch sensor according to claim 1, wherein the first substrate has a first surface and a second surface, the first optically transparent adhesive layer is disposed between the cover plate and the first surface, The first plurality of networked silver nanostructures are disposed on the second surface. 4. The touch sensor according to claim 3, further comprising a second base transparent conductor and a second optically transparent adhesive layer, wherein the second optically transparent adhesive layer is disposed between the second base transparent conductor and the first between the base transparent conductors. 5. The touch sensor of claim 4, wherein the second optically clear adhesive layer is compatible with the first plurality of interconnected silver nanostructures, the second optically clear adhesive layer and the first plurality of interconnected silver nanostructures. The mesh silver nanostructures are in direct contact with each other. 6. The touch sensor of claim 5, wherein the second base transparent conductor has a second substrate and a second plurality of networked silver nanostructures. 7. The touch sensor of claim 6, wherein the first plurality of networked silver nanostructures or the second plurality of networked silver nanostructures comprise silver nanowires. 8. The touch sensor of claim 7, wherein the silver nanowires have an aspect ratio in the range of 10 to 100,000. 9. The touch sensor of claim 1, wherein the light transmittance (T%) of the first plurality of networked silver nanostructures is at least 50%, at least 60%, at least 70%, at least 80% , at least 91% to 92%, or at least 95%. 10. The touch sensor of claim 1, wherein the haze of the first plurality of networked silver nanostructures is no more than 10%, no more than 8%, no more than 5%, no more than 2%, no more than 1% , not more than 0.5%, or not more than 0.25%.

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